razor sharp blade
by dazai-san
Summary: In the aftermath of the Kyuubi attack, Iwa finds it the perfect chance to strike out at Konoha, sparking another war between the two nations. Desperate after only barely defending itself, Konoha forces Naruto, the container of the Kyuubi, under the tutelage of ANBU Wolf to become the perfect weapon for Konoha. [au]
1. Chapter 1

**Title:** razor sharp blade

 **Summary:** In the aftermath of the Kyuubi attack, Iwa finds it the perfect chance to strike out at Konoha, sparking another war between the two nations. Desperate after only barely defending itself, Konoha forces Naruto, the container of the Kyuubi, under the tutelage of ANBU Wolf to become the perfect weapon for Konoha. [au]

 **Warnings:** Heterosexual _and_ homosexual relationships, AU, unbetaed, slow pacing (for me, at least), swearing, violence, possible OOC, major and minor OCs, spoilers for Kakashi Gaiden, eventual strong-Naruto, future canon character deaths, etc.

 **Pairings:** future SasuNaru and ObiKaka; other minor pairings as well. Mild Minato/Kushina

 **Notes:** Hey look another project. Yay.

I don't own Naruto. Don't even understand why I need this here.

.

Prologue

" _Only the dead have seen the end of war." – Plato_

Konoha… is not doing well.

How can they, when thousands have lost their lives, and many, many more have lost their loved ones?

The Kyuubi is sealed now, into the body of a baby boy merely two days of age. His father and mother will be hailed as heroes, but that will do nothing to ease the baby's pain of growing up alone without a mother's nurturing and father's guidance.

People will direct their hate filled looks at Naruto, a _baby_ , for something he has no control over, for doing _nothing_ but become a prison _(a sacrifice)_ for the monster that destroyed homes and lives.

Sarutobi Hiruzen leans forward, burying his face in his hands and tries very, very hard not to weep for the child's fate.

.

Bile rises in Kakashi's throat, making it hard to breathe, and his eye stings, Obito's already weeping and soaking the navy cloth of his hitai-ate.

 _It's only been three days—and we're being attacked._ Kakashi can really only think of the unfairness of it all, but he closes his eye briefly, reminding himself that the world isn't fair. He of all people should know that.

He swallows, opening his eye once more, and adjusts his Wolf mask, adopting his ANBU persona immediately, deigning to ignore the roiling of turbulent emotions in the pit of his stomach. "Evacuate the area immediately," he shouts loudly, voice clear.

A kunai slips into his hand, its cold weight familiar to his gloved hands as he launches himself at an enemy shinobi going after a fleeing civilian boy, knocking him to the ground and slitting his throat before he can so much as flail. Kakashi only spares his hitai-ate a cursory glance before jumping away from him to go for the next shinobi.

 _Iwa. Why am I unsurprised?_ Kakashi muses internally, perhaps a little bitterly, as he rolls under a fire jutsu sent his way, kicking the attacker's feet from under him and stabbing down, only for his blood soaked kunai to meet steel instead of flesh.

The ANBU jumps back, raising his kunai defensively, studying his enemy closely while still alert for other attackers. His enemy has a mask covering his entire face save the slanted green eyes, and his choppy and short hair is tied up high.

Kakashi quickly deflects a kunai sent his way, the weapon hitting his with a _klang_ and hitting the (once again) bloodstained ground.

A bright whitish blue glow is the only indication Kakashi gets before the exploding tag goes off, pervading the air with an acrid burning smell that fills Kakashi's hypersensitive nose along with a thick white cloud soon after. He almost coughs, but holds his breath, for the noise will alert the enemy to one of his weaknesses and his location.

Grimacing, Kakashi pulls out one of his own exploding tags and ties it to his kunai surreptitiously, always listening. Despite the noises of shinobi fighting and weapons clashing, it's still eerily silent, though that may have to do with the pure _white_ surrounding him.

He hears the whisper of cloth, and a very sharp breath that is almost inaudible, but Kakashi whirls around, throwing the kunai in the slightly fading cloud of white. When he hears an involuntary grunt of pain, he assumes the kunai hit its target and when he hears a thud soon after, he jumps in the opposite direction as his exploding tag goes off.

The force from the explosion clears most of the white cloud away, but its heat also singes Kakashi's clothing from the back of his knee and down. He lands on his feet neatly, and when he hears a curse from the other shinobi, he takes a set of shruiken and throws them all in the general direction of the curse.

When Kakashi gives the shinobi (now with half their face mask burnt off) a closer look as the nin leaps out of the trajectory of his shruiken, he corrects himself. _Kunoichi._ Not that it matters what gender his opponent is.

After all, whether the kunoichi is male or female, she is still an enemy of Konoha, and therefore must be treated accordingly. Kakashi quickly slides up his hitai-ate beneath his Wolf mask, and the Sharingan whirls to life, its color a bloody red.

The kunoichi, clearly recognizing the Kekkai Genkai, takes an unconscious step back, and Kakashi allows himself a grim smile as he forms the hand seals for Chidori, electricity crackling along the length of his hand.

The next moment, his hand is protruding through her chest, and the kunoichi sags, limp and very clearly dead as Kakashi withdraws his blood soaked hand, already feeling the telltale buzz of dizziness in the back of his head from mild chakra exhaustion.

He slides the hitai-ate over Obito's eye, feeling the drain of chakra disappear immediately, and looks around for anybody who might need help. Upon seeing nobody in the nearby vicinity, Kakashi quickly collects his weapons and heads after the civilians with a kunai in hand.

As he rounds the corner, he spots a team of Konoha ANBU heading the same direction as him, and nods slightly before making the private hand signal for _Konoha_ to signal that he's one of them. They do the same, and Kakashi falls into step with Tiger.

The five ANBU are on alert, and at the first sign of possible trouble, one of them heads off to fix it. After hearing a high pitched scream, Tiger leaves Kakashi's side immediately, while Bee heads in the direction of a puff of smoke.

" _Boo_ ," purrs a voice in Kakashi's ear, and immediately he whirls around, kunai in hand, but it's too late when something sharp digs its way into the flesh of Kakashi's side, missing his heart (which is what Kakashi assumes the shinobi had been aiming for) only because of Kakashi jumping and turning.

Black creeps in around his vision, and he feels something coppery and wet at the back of his throat. His fingers nearly slip around the blade of the kunai, and he pulls back, just as the enemy pulls his weapon out of Kakashi's side as the ANBU gives a gasp of pain.

Cat grabs his arm to prevent him from collapsing, sliding an arm under Kakashi's knees as well and through his hazy vision, sees him nod briefly at the remaining two ANBU members, Fox and Bear, for them to deal with the enemy.

Then he passes out.

.

He wakes with a gasp, only to wince when it strains the injury in his side. "Easy there, Hatake-san," murmurs the medic sitting in the tent, and Kakashi can see dark bags under the medic's eyes. _Since I'm in a tent and not captured or being tortured, I suppose we drove the Iwa off…_

"Cat?" Kakashi tries to ask, but his voice cracks, most likely from lack of water. Nevertheless, the medic understands, standing up from his seat and wordlessly handing him a glass of the fluid before turning away politely so Kakashi can drink, a gesture that Kakashi appreciates immensely.

"The ANBU who carried you in? Has a short scratch on his stomach. Awake already. He'll be fine."

Kakashi breathes out a sigh of relief—at least Tenzo's fine.

"Do you want to see him?"

"If it is possible."

The medic ducks out of the tent, and after a few moments, returns with Tenzo in tow. His kohai brightens imperceptibly, and the medic gives them their space by heading outside once more.

"Kakashi-senpai," Tenzo greets him, with a faint and relieved smile. "How are you feeling?"

"Alright. I don't think I'll be able to move for a while though." Kakashi grimaces. "Fox and Bear?"

Tenzo's small smile drops off his face, and that's everything that Kakashi needs to know. He bows his head slightly. "Oh."

"Bee has a dislocated shoulder, and Tiger has a few pretty bad burns from explosive tags," Tenzo adds, and it's a clearly an attempt to keep Kakashi's mind away from Fox and Bear. "They're resting up in another tent."

Kakashi draws in a shaky breath, running one hand through his messy silver hair, pulling sharply and relishing the small amount of pain it brings—anything to distract himself from another two teammates lost—the other clutching the green blanket his legs are tangled in. "The shinobi who got me?"

"Dead. Fox took him out with him."

He closes his eye, squeezing it shut to prevent himself from crying. _Shinobi don't show their emotions. ANBU_ have _no emotions. A shinobi must not show his tears. ANBU_ have _no tears to cry._

"I'm sorry," says Tenzo quietly. _For being the bringer of the news._

"Why?" Kakashi asks, voice hoarse for a reason other than a lack of water, and he's not asking Tenzo why he's sorry. _Why is war so unfair?_

"I don't know," Tenzo replies, tone soft, and understanding his meaning.

He turns away, pretending not to hear the sob escape from Kakashi's throat.

.

 **a/n:** I wondered what the Naruto series would look like if Naruto grew up in an era of war instead of peace. This was born.

Leave a review, telling me what you think? I really appreciate feedback and constructive criticism.

And by the way, this fic isn't just getting a plot bunny out of the way like "burning flames of will". I actually intend to continue it.


	2. Chapter 2

" _Instead of sighing about the past, I'd rather be happy to face the present." – Oz Vesalius (Pandora Hearts)_

[Chapter Summary: Kakashi is forced to move on.]

.

"Tenzo, what am I supposed to _do_ with a child?"

His kohai gives him a flat and steely look. "You love him."

.

And Kakashi _does_ love the child, but he can't help but see Minato in his blonde hair and bright blue eyes, or Kushina and Obito in his boisterous personality, or Rin in the way he treats certain things with gentle care.

It hurts so much, and it isn't fair to Minato's son— _Naruto_ —either, because Kakashi feels like he's loving him for the people he reminds him of rather than for himself.

Tenzo thinks that's bullshit, and doesn't hesitate in telling him so. While Kakashi is thankful to his friend for all he's done and his vote of confidence, he isn't sure he's right despite what he tells him.

It's also tough, leaving the three year old in the care of somebody else so frequently when he's forced onto the battlefield, especially when Naruto turns his large blue _(Minato's, just a few shades lighter)_ eyes on him brimming with unshed tears and Kakashi resolves to stay alive, if only for the child.

And of course he does. He goes, fights, kills, and returns injured but alive. And while the battlefront is hell, especially with shinobi staying behind to protect civilians and help rebuild the village, coming home is always worth it, because there's _(for the first time in a long time)_ somebody at home for him.

.

The moment Naruto turns five, Kakashi doesn't hesitate in telling him he's a jinchuriki. Doesn't hesitate in telling him that it's not his fault. Doesn't hesitate in telling him that he's still loved, and that he's a _hero_ , not a monster. That the monster is the creature sitting in his stomach.

(The Sandaime had refused to give out Naruto's jinchuriki status despite Minato-sensei's wishes. While Kakashi loves his teacher dearly, holds him close to his heart, he agrees with the Sandaime, for Naruto would be hated and the status would paint an obnoxiously bright target on his back.)

Five is also when Kakashi begins training his protégé and he hates it. He hates it so, so much, because this is a _five year old boy_ and Kakashi knows what it's like not to have a childhood, knows it hurts so much to be missing something everybody else has, and it hurts even more because he's doing this to somebody else.

("Naruto," he had said, "please don't change too much. You might be a tool for Konoha, but you must remember that you're human too. It'll be hard, but be both. For me. For you.")

Kakashi tries his best to keep two personalities—the Wolf one, when he trains him, and himself, the _Kakashi_ one, to take care of him.

Frankly, it's exhausting, and it terrifies him exactly how much of a weakness for Kakashi that Naruto has become—it terrifies him that he wouldn't know what to do should the boy die, or turn his back on him. Hell, it very nearly breaks what's left of his heart into millions of tiny little pieces when Naruto gets hurt, if even only a little bit.

 _(He doesn't remember when "Minato's son" turns into "Naruto".)_

("See?" Tenzo had said, and Kakashi could have seen hints of smugness in his kohai's dark eyes. "That drivel you were spouting about you not loving Naruto for himself—yeah, bullshit."

Maybe, just _maybe_ , Kakashi can believe him a little bit now.)

.

The first thing Kakashi teaches Naruto is to love his teammates, comrades, precious people, _family_. That they are worth dying for.

(Naruto had blinked and nodded seriously. "You're family, right?" he had asked, and Kakashi had simply dipped his head. The slight movement had been enough to convey what Kakashi had meant.)

.

When Naruto has turned seven, he has already taken too many lives to count, and has a page in the Bingo Book as a chuunin-ranked ninja. (He's not as young as Kakashi was but it's too close, _just a year…_ )

It disgusts Kakashi in so many ways and tears at all of his morals and the remains of his heart and makes him want to sob desperately at the same time he wants to rip whoever created fate to pieces for making Naruto suffer such a cruel one.

It also hurts so much because he knows Naruto hates it like Kakashi does but not possibly as much because Kakashi knows it's _his_ fault.

Yet somehow through the bleak days, through the horrible assassinations, through the bloody days on the battlefront, Naruto retains his sunny personality and manages a smile for Kakashi, and he loves and hates it at the same time.

He loves it because Naruto is still a _child_ at heart.

He despises it because if he were to die, Naruto would break. And it'd be his fault.

 _(He doesn't want to be a liability, not for anyone, especially not for Naruto.)_

.

For all that Naruto is a genius at fighting, he is still _stupid_.

("Who's the Shodaime, Naruto?"

"Uh… Tobirama Namikaze?")

So when the Academy begins another year, Kakashi enrolls Naruto into it.

It's not just for the education, and when he returns every day, Kakashi is satisfied to see that he seems so much _happier_ , even if he has to hide his Chuunin status _(subterfuge)_ and play the role of the _dead last_ in the class.

("Sakura-chan is so nice!"

"I totally _let_ Sasuke-teme win!"

"Kiba helped me prank the mean sensei today!"

"Hey, Hinata-chan turns red whenever I talk to her. Is she sick?"

"We got a new sensei today! He's only seventeen though, and his name is Iruka! He's so nice to me, and even though I'm not smart, he doesn't make fun of me like the old sensei did to me and Kiba and Lee-senpai and—"

It goes on.)

.

When Naruto turns nine, he graduates with flying colors.

When Naruto turns nine, he is officially Kakashi's student.

When Naruto turns nine, he is a tokubetsu jounin. Kakashi hates it.

.

The day Kakashi officially becomes Naruto's jounin-sensei brings with it a surprise.

"Assigned to Kakashi Hatake is Naruto Uzumaki, Sasuke Uchiha, and Sakura Haruno."

… _What?_

"What?" Kakashi blurts out, shocked enough to let the word slip through his throat and embarrassingly, Iruka-sensei pauses and he and the rest of the jounin-sensei turn to give him quizzical looks.

He clears his throat awkwardly, flipping the matter in his mind. _The Sandaime gave me three geniuses to work with?_

"I'm—I assumed I'd be working with Naruto alone, but…" He laughs a little sheepishly, rubbing the back of his neck awkwardly. "It seems the Hokage-sama has other plans for me. I apologize for my interruption."

Sitting in his seat, Naruto waves his hands frantically in what Kakashi recognizes as ANBU hand signs. _Kaka-nii, I'm with_ _ **SASUKE**_ _!_ (The personal sign Naruto had given Sasuke was _originally_ the middle finger but with a reproving glare from Kakashi, he'd sulkily changed it to the sign for _duck_ combined with _butt_.)

Stifling a laugh, Kakashi shifts from one foot to the other and subtly signs back, _Well, no need to hide that you're better than him now, hmm?_

Naruto breaks into a grin, much to his peers' odd glances.

Iruka clears his throat, blinking in genuine confusion. "And might I ask why Naruto wouldn't be assigned to a genin team, Kakashi-san?"

"I'm sorry, but that's classified," Kakashi murmurs, shifting again. "And I had assumed… please continue."

Coughing slightly, Iruka nods, still looking curious, as he continues.

Once he comes to the end of the list and folds the paper up, Iruka announces, "Come down to introduce yourselves to your jounin-sensei."

With a loud _whoop_ , Naruto jumps out of his seat and races towards Kakashi with a bright grin and Kakashi has a good (or _bad_ ) feeling about what's going to happen next.

"Kakashi-nii-chan!" singsongs Naruto as he tackle-hugs him and very near chokes him as he wraps arms around his shoulders, and Kakashi gets a very good look at the conniving smirk on the nine year old's face that frankly terrifies Kakashi more than it should.

All activity in the room drops from about sixty percent to zero in a second.

"Naruto, you're going to _choke_ me," he wheezes after a few moments of pure silence.

" _The_ Sharingan no Kakashi is your _nii-chan?_ " Sasuke demands incredulously as Kakashi extricates himself from Naruto's grip.

Naruto grins.

(The sneaky, _sneaky_ little shit.

He must've been waiting his entire time at the Academy to pull this on them.)

.

"So," Kakashi begins, "let's introduce ourselves. Name, hobbies, dreams for the future, likes, dislikes, things like that. I'll go first.

"I'm Kakashi Hatake. I've got a few hobbies, quite a few likes, I dislike a lot… dreams for the future? Hmm…"

Naruto rolls his eyes. "Kaka-nii-chan likes reading, eggplants and miso soup— _together_ , it's _gross_ —he dislikes being interrupted when sleeping and reading, and I don't know… what _is_ your dream?"

 _Party-pooper._

"Introduce yourself first, Naruto. And it's _Kakashi-sensei_."

"Whatever, nii-chan. I'm Naruto Uzumaki! I like ramen and Kaka-nii-chan! I dislike waiting for anything, especially ramen! I like pranks, especially when Kiba helps me! My dream is to be a good shinobi!"

Kakashi smiles a little behind his mask. "And you, pinkie?"

Sakura gives a huff and a glare, but the short and choppy _pink_ hair kills the effect. "I'm Sakura Haruno. I like being right, and I hate it when certain people"—here she glares at Naruto—"interrupt my reading time. My hobbies are reading and hanging out with Ino. My dream is to become a good kunoichi that people _respect_ because I've seen how kunoichi are treated."

 _A genius in mind,_ Kakashi muses. _She and Naruto will make an excellent team._ He pauses. If _they learn how to be civil to each other._

"And you?"

Sasuke begins with almost as much enthusiasm as Naruto, "I'm Sasuke Uchiha! I like tomatoes and Itachi-nii-chan. I really hate it when aniki does that annoying forehead poke thingy. My hobbies are training with aniki when he has the time. My dream is to be a good shinobi like Itachi!"

… _Wow. His life is centered around Itachi, huh._

"Itachi was my kohai in ANBU," Kakashi says mildly only to regret it the moment Sasuke's eyes light up and opens his mouth.

.

They pass the bell test beautifully, and Naruto almost, just _almost_ , touches the bells several times, only to growl in frustration when Kakashi dances out of the way, making it look _so damn easy_ while reading a book.

(He's not actually reading. He's only doing it to infuriate his cute little students.)

(Where the hell did that _cute_ comment come from?)

(Admittedly, they _are_ adorable, especially when Naruto scowls and looks ridiculously like Pakkun, or when Sasuke puffs out his cheeks and makes Kakashi have this ridiculous urge to poke them, or when Sakura crosses her arms and tries to look mature but utterly _fails_ because she's, well, _adorable_.)

Kakashi hides a smile when Sakura finally figures out that the point of the exercise is to practice _teamwork_ , and he knows he was right in expecting her to figure it out.

The bells remain untouched but he passes them with new information on his genin to mull over for the next few days.

Sakura is the genius in mind. Naruto is the genius in body. Sasuke is an even mix of the two.

The Sandaime is betting a huge gamble on him, and Kakashi feels quite honored.

If trained properly, this team could surpass the Sannin and beyond.

Kakashi isn't sure if he wants that.

He knows his students want that.

.

 **a/n:** Hi.

Look, I updated. _AMAZING._

This chapter is more or less a background for the story, so it's not quite… _story-telling_ , if you know what I mean. The writing style here differs, if only subtly, and that's mostly because one is more poetic, one is more _I'm reading a story_.

Technically, both this chapter and last chapter can be considered prologues, as in _setting the scene_ for the story. But they don't mesh together, thus making it two separate chapters. The story _truly_ begins when Naruto is nine.

Also, I'm addressing some issues readers might have here:

 **One:** Naruto is still an idiot.

 _That is because Naruto_ **is** _an idiot._

In the _Naruto_ franchise, that has been made very, very **clear** , and I do not intend to change that fact. Oh, certainly, Naruto will start out stronger, simply because of the training, but Naruto was intended to be the MC _and_ the character that creates the need for the exposition character, aka _Sakura_.

I'm not going to suddenly make Naruto all perceptive and all-knowing and _brilliant_ because _he is not_. At the very core of his being, Naruto is a cheerful idiot who _does_ have his moments of genius but _not all the time._ And while he might be _slightly_ smarter than he is in franchise, that's only because Kakashi is desperately trying to beat the stupid out of him.

This is an AU for one thing: the Naruto timeline is that of a _war_ , and not of peace. I'm not changing the core of the characters. This story is how I imagine the characters will turn out if they were born into wartimes, if they're born at all.

 **Two:** Sakura/Sasuke are not the same person as they are in canon.

That's because _they aren't_.

Sakura isn't an insanely obsessed fangirl who hates Ino and Naruto here because _she has no time for that._ She's growing up to be a _kunoichi_ in _wartimes_ , and I hate how her intellect is so _downplayed_ in canon. She's smarter than _Sasuke "Rookie-of-the-Year" Uchiha_ , as Sasuke himself has said before.

Sasuke isn't an angsting, broody asshole because his family _hasn't been massacred_. Read/watch some of the episodes/chapters of Naruto that cover Sasuke's childhood—he's a cheerful, immature, and adorable brat who loves his brother too much. He retains the core of those traits, but he _has_ grown up a little due to wartimes.

The Uchiha Clan Massacre hasn't happened either because _even Danzo isn't that crazy_. He's not going to risk a coup d'état to slaughter a _huge amount of the shinobi force_ that will be _vital_ to the war effort. He'll wait until the end of the war, if he's still alive by then.

 **Three:** Kakashi.

Well, the Sandaime gave him orders to take care of Naruto and turn him into a weapon.

Sure, if Kakashi had been his pre-Obito's-"death" self, he probably would've done it to the letter.

He's not his pre-Obito's-"death" self though.

He's just been through his teacher's death and Naruto's really the only thing he has _left_ and in canon, he left him alone. If he had a choice here, Kakashi probably would've.

But he doesn't have a choice. And therefore, _Kakashi is forced to move on_.

I'm done explaining myself.

If you have any issues, please feel free to review.

Actually, please, _please_ drop a review either way. Constructive criticism is welcomed with open arms.

*Please note that this is unbetaed. I do _not_ have a beta and I do _not_ wish for one. All of these chapters are written and proofread by one person (me) so please don't rip on me for one tiny little grammatical error.*


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